A storage system connected to a host computer (client) via a network has multiple HDDs as storage devices for storing data, for example. Deduplication is an example of an art for reducing the amount of storage data when storing data to the storage device to reduce the costs of storage media. In deduplication, data segments storing the identical contents in files are contracted to reduce the total amount of data capacity stored in file systems and storage systems.
There are cases where a storage system adopting a cluster configuration is utilized with the aim to increase the speed and availability of the deduplication process. In that case, data having identical contents may exist among different nodes of the cluster configuration, and the deduplication efficiency in the cluster configuration can be improved by performing deduplication of data having the same contents. Patent Literature 1 teaches an art related to this technique, which discloses a method for performing deduplication among nodes by providing a master server for managing deduplication information of respective nodes.